1. Field of the Invention
The invention relates to a control unit for an injection moulding machine or the like with a keyboard for inputting data and at least one function key set for controlling the operation of the machine.
2. Prior Art
With modern injection moulding machines the injection moulding conditions and the operation or sequence of the machine are computer controlled. When changing moulded components produced under mass production conditions it is necessary for new data and parameters for the production process to be established and stored. This generally occurs by way of a separate key set. Interventions in the production sequence on the other hand are performed by way of at least one further function key set.
A screen in the nature of a monitor, for instance a liquid crystal or plasma screen, can be used with computer controlled injection moulding machines as a display or indicating device. Data input during the setting up process, monitoring information and even a complete menu can be displayed on it. The use of a screen is, however, not possible without problems under the relatively rough production conditions in operational use of an injection moulding machine. The screen has a large working surface and is particularly sensitive to impacts in the screen region. However, damage to the screen conceals an additional risk of personal danger.
Tests conducted by the applicant have shown that mechanical damage of the sensitive front side of the screen when actuating the control unit and when retrieving information via the screen occurs only seldom, if at all. When inputting and retrieving information the operative concentrates on viewing the screen. This basically gentle treatment of the sensitive screen consequently coincides with those times at which the screen exhibits its greatest usefulness; that is during the inputting of data during the setting up of the functional process of the injection moulding machine. During the production sequence of the machine, which is generally automatic, on the other hand, little current information is required and displayed. During these substantially more extended and more frequent phases the probability of mechanical stressing of the control unit by uncontrolled impacts or movements of the operative is highest by a long way.